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ADS7128:ADS7128

TAKAHIKO NAKANISHI
Prodigy 10 points
Part Number: ADS7128

Tool/software:

We perform LOG analysis on product applications and firmware.
The following points need to be confirmed.

【分析結果の詳細】

LOG解析の結果、以下の現象が確認されました。

現象の概要 電源を切る
とADCからの応答がACKと判定されますが、その際に受信したデータはすべて0xFF(すべてFF)です。

関連ログ
の抜粋 2024-07-18 02:27:46.4533 [デバッグ] No59 T4- RCV:10-02-76-00-00-00-FF-FF FF - FF - FF - FF-FFFFの- FF - FF - 10から03

詳細な現象
電源OFF指示が出た直後は、ADCからの応答をACKとして記録しますが
、受信したデータはすべて0xFF(すべてFF)であり、通常のデータとは異なります。

確認事項
この現象がハードウェアの正常な動作か確認してください。
また、異常動作がございましたら、原因とhをお教えいただけますと幸いです

  • 0
    TI__Expert 5290 points

    Hi Takahiko,

    I attempted to translate this into English, but am still having a hard time understanding the question. Could you reformat and resubmit?

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 10 points

    Hi　Joel

    > I attempted to translate this into English, but am still having a hard time understanding the question. Could you reformat and resubmit?

    ＜question.1＞
    We perform LOG analysis on product applications and firmware.
    The following points need to be confirmed.

    ■Details of analysis results

    As a result of LOG analysis, the following phenomena were confirmed.

    ■Summary of the phenomenon
    When the power is turned off, the response from the ADC is judged as an ACK, but all the data received at that time is 0xFF (all FF).

    ■Excerpt of the relevant log
    2024-07-18 02:27:46.4533 [DEBUG] No59 T4- RCV:10-02-76-00-00-00-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF- FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-FF-10-03

    ■Detailed phenomena
    Immediately after the power off instruction is issued, the response from the ADC is recorded as an ACK.
    However, all the received data is 0xFF (all FF), which is different from normal data.

    ■Confirmation items
    Also, if there is any abnormal behavior, please let us know the cause and how to correct it.
    I would be happy if you could.


    ＜question.2＞
    Immediately after the power off instruction is issued from the PCB, the response from the ADC is recorded as an ACK.
    However, all the received data is 0xFF (all FF), which is different from the normal data.
    Please let me know what is the correct way for the data to be received in that case.

    ＜question.3＞
    Immediately after the power off instruction is issued from the board, the response from the ADC is recorded as an ACK.
    Please tell me what the correct SDA and SCL data should be (Hi or Low) at that time.


    Regards,
    Takahiko

  • 0 in reply to TAKAHIKO NAKANISHI
    TI__Expert 5290 points

    Hi Takahiko,

    This seems to be the correct operation, as the I2C lines shared between the host and device are pulled up high with resistors since these pins are in the open-drain configuration. To the controller, this would look like a data stream of all F's. If you have any more concerns, it would be helpful to send an oscilloscope capture of the SDA line as soon as power is turned off to the device.

    Regards,
    Joel

  • 0
    Prodigy 10 points

    Hi　Joel

    After power off,
Please tell me how the ACK/NACK and SDA lines operate.

    Regards,
    Takahiko
  • 0 in reply to TAKAHIKO NAKANISHI
    TI__Expert 5290 points

    Hi Takahiko,

    The device does not have a specific ACK/NACK line. An ACK bit (low) is sent by the device taking control of the SDA line and pulling it down. A NACK bit (high) is sent when the device does not understand the data, doesn't receive it, cannot initiate communication with the host, or another condition, and so the SDA line remains pulled high.

    If you would like some help in investigating this further, could you send an oscilloscope capture of the I2C lines once the device is powered off? This would allow me to see the specific voltage of the SDA line at this time.

    My other question would be, how are you monitoring the SDA bit-stream after the device is powered off? With a logic analyzer or another method?

    Regards,
    Joel

  • 0 in reply to Joel Meraz
    Prodigy 10 points

    Hi　Joel

    Thank you

    I will take a look at the document.

    <question2>

    In the situation of the circuit due to the power-off,
    1. To acquire the temperature by I2C communication from the connector
    　board (camera module) on the temperature data side
    　(It is assumed that this line will be Power-Off, I2C communication
    　will be NACK, and SDA signal will be = Hi)
    2. To acquire the current value by I2C communication from the circuit onthe ADC side
    　At these 1 and 2 timings, the ACK/NACK and SDA lines of I2Ccommunication become Hi/Low.
    　　This is the point of the answer, so could you please check it again?

  • 0 in reply to TAKAHIKO NAKANISHI
    TI__Expert 5290 points

    Hi Takahiko,

    It seems like you are referencing something that is taking the temperature of a camera module. Is this correct? I don't believe I currently have the full context of what you are asking. Could you please rephrase your inquiry to provide more clarification into the matter? 

    My current understanding is that you have a temperature probe monitoring the temperature of a camera module, and the output of the temperature probe is being read by the ADS7128. I'm not certain on what the question is that you are asking with regard to the ACK/NACK bit. Please correct me if I am mistaken.

    Regards,
    Joel